/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * See LICENSE.txt included in this distribution for the specific
 * language governing permissions and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at LICENSE.txt.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
 */

package org.opensolaris.opengrok.history;

import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.Reader;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Date;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.opensolaris.opengrok.util.Executor;
import org.opensolaris.opengrok.util.IOUtils;

/**
 * Parse source history for a Perforce Repository
 *
 * @author Emilio Monti - emilmont@gmail.com
 */
public class PerforceHistoryParser {

    /**
     * Parse the history for the specified file.
     *
     * @param file the file to parse history for
     * @param repos Pointer to the {@code PerforceRepository}
     * @return object representing the file's history
     * @throws HistoryException if a problem occurs while executing p4 command
     */
    static History parse(File file, Repository repos) throws HistoryException {
        History history;

        if (!new PerforceRepository().isRepositoryFor(file)) {
            return null;
        }

        try {
            if (file.isDirectory()) {
                history = parseDirectory(file);
            } else {
                history = getRevisions(file, null);
            }
        } catch (IOException ioe) {
            throw new HistoryException(ioe);
        }
        return history;
    }

    private static History parseDirectory(File file) throws IOException {
        ArrayList<String> cmd = new ArrayList<String>();
        cmd.add("p4");
        cmd.add("changes");
        cmd.add("-t");
        cmd.add("...");

        Executor executor = new Executor(cmd, file.getCanonicalFile());
        executor.exec();
        return parseChanges(executor.getOutputReader());
    }

    static History getRevisions(File file, String rev) throws IOException {
        ArrayList<String> cmd = new ArrayList<String>();
        cmd.add("p4");
        cmd.add("filelog");
        cmd.add("-lt");
        cmd.add(file.getName() + ((rev == null) ? "" : "#"+rev));
        Executor executor = 
            new Executor(cmd, file.getCanonicalFile().getParentFile());
        executor.exec();

        return parseFileLog(executor.getOutputReader());
    }

    private static final Pattern REVISION_PATTERN =
        Pattern.compile("#(\\d+) change \\d+ \\S+ on (\\d{4})/(\\d{2})/(\\d{2})"
            + " (\\d{2}):(\\d{2}):(\\d{2}) by ([^@]+)");
    private static final Pattern CHANGE_PATTERN =
        Pattern.compile("Change (\\d+) on (\\d{4})/(\\d{2})/(\\d{2}) "
            + "(\\d{2}):(\\d{2}):(\\d{2}) by ([^@]+)@\\S* '([^']*)'");

    /**
     * Parses the history in the given string. The given reader will be closed.
     *
     * @param fileHistory String with history to parse
     * @return History object with all the history entries
     * @throws java.io.IOException if it fails to read from the supplied reader
     */
    protected static History parseChanges(Reader fileHistory) throws IOException {
        /* OUTPUT:
        Directory changelog:
        Change 177601 on 2008/02/12 by user@host 'description'
         */
        History history = new History();
        List<HistoryEntry> entries = new ArrayList<HistoryEntry>();
        BufferedReader reader = new BufferedReader(fileHistory);
        String line;
        Matcher matcher = CHANGE_PATTERN.matcher("");
        while ((line = reader.readLine()) != null) {
            matcher.reset(line);
            if (matcher.find()) {
                HistoryEntry entry = new HistoryEntry();
                entry.setRevision(matcher.group(1));
                int year = Integer.parseInt(matcher.group(2));
                int month = Integer.parseInt(matcher.group(3));
                int day = Integer.parseInt(matcher.group(4));
                int hour = Integer.parseInt(matcher.group(5));
                int minute = Integer.parseInt(matcher.group(6));
                int second = Integer.parseInt(matcher.group(7));
                entry.setDate(newDate(year, month, day, hour, minute, second));
                entry.setAuthor(matcher.group(8));
                entry.setMessage(matcher.group(9).trim());
                entry.setActive(true);
                entries.add(entry);
            }
        }
        IOUtils.close(reader);
        history.setHistoryEntries(entries);
        return history;
    }

    /**
     * Parse file log. Te supplied reader will be closed.
     *
     * @param fileLog reader to the information to parse
     * @return A history object containing history entries
     * @throws java.io.IOException If it fails to read from the supplied reader.
     */
    protected static History parseFileLog(Reader fileLog) throws IOException {
        BufferedReader reader = new BufferedReader(fileLog);
        List<HistoryEntry> entries = new ArrayList<HistoryEntry>();
        String line;
        HistoryEntry entry = null;
        while ((line = reader.readLine()) != null) {
            Matcher matcher = REVISION_PATTERN.matcher(line);
            if (matcher.find()) {
                /* An entry finishes when a new entry starts ... */
                if (entry != null) {
                    entries.add(entry);
                    entry = null;
                }
                /* New entry */
                entry = new HistoryEntry();
                entry.setRevision(matcher.group(1));
                int year = Integer.parseInt(matcher.group(2));
                int month = Integer.parseInt(matcher.group(3));
                int day = Integer.parseInt(matcher.group(4));
                int hour = Integer.parseInt(matcher.group(5));
                int minute = Integer.parseInt(matcher.group(6));
                int second = Integer.parseInt(matcher.group(7));
                entry.setDate(newDate(year, month, day, hour, minute, second));
                entry.setAuthor(matcher.group(8));
                entry.setActive(true);
            } else {
                if (entry != null) {
                    /* ... an entry can also finish when some branch/edit entry 
                     * is encountered */
                    if (line.startsWith("... ...")) {
                        entries.add(entry);
                        entry = null;
                    } else {
                        entry.appendMessage(line);
                    }
                }
            }
        }
        IOUtils.close(reader);
        /* ... an entry can also finish when the log is finished */
        if (entry != null) {
            entries.add(entry);
        }

        History history = new History();
        history.setHistoryEntries(entries);
        return history;
    }

    /**
     * Create a Date object representing the specified date.
     *
     * @param year the year
     * @param month the month (January is 1, February is 2, ...)
     * @param day the day of the month
     * @param hour of the day
     * @param minute of the day
     * @param second of the day
     * @return a Date object representing the date
     */
    private static Date newDate(int year, int month, int day, int hour, int minute, int second) {
        Calendar cal = Calendar.getInstance();
        // Convert 1-based month to 0-based
        cal.set(year, month - 1, day, hour, minute, second);
        return cal.getTime();
    }
}